Field of the Invention
The present invention generally relates to wireless communication networks, such as radiomobile or cellular networks. More particularly, the present invention relates to protection of “Global Navigation Satellite System” data reception during uplink data transmission based on Carrier Aggregation in a cellular network compliant with LTE/LTE-A technology.
Overview of the Related Art
Cellular networks, such as cellular networks compliant with LTE/LTE-A technology, allow data to be high-speed conveyed between a fixed-location transceiver base station (or network node) and user equipments (e.g., user terminals, such as cellular phones, smartphones, tablets) associated therewith (e.g., within a network cell identified by the network node).
In current LTE/LTE-A specifications Carrier Aggregation functionality has been introduced, which allows concurrent use of several carriers (usually referred to as aggregated or component carriers) at respective frequencies to provide an aggregated bandwidth (e.g., up to 100 MHz) in order to meet “International Mobile Telecommunications-Advanced” (IMT-Advanced) requirements for high data rates.
A very common type of user equipment presently available on the market also embeds a “Global Navigation Satellite System” receiver (hereinafter, GNSS receiver) for receiving signals (hereinafter, GNSS signals) that comprise data (hereinafter, GNSS data) providing accurate current position of the user equipment, when required.
However, degradation in reception of the GNSS signals may be experienced when uplink data transmission based on Carrier Aggregation (hereinafter, Carrier Aggregation uplink data transmission) takes place and when GNSS signals reception is enabled. Indeed, due to non-linear signal processing, when two (or more) signals are transmitted on different frequencies (such as in Carrier Aggregation uplink data transmission), undesired “InterModulation Distortion” (IMD) signals result in portions of the spectrum. These IMD signals comprise signals at harmonic frequencies (i.e., at integer multiples) of the carriers frequencies, as well as signals at the sum and difference frequencies of the carriers frequencies and at harmonic frequencies thereof.
Thus, when IMD signals fall within the GNSS receiver band, degradation in reception of the GNSS signals may be experienced.
Paper R4-145947, “How to handle IMD interference for GNSS”. NTT DOCOMO, INC., Jun. 10, 2014, 3GPP TSG-RAN WG4 Meeting #72bis generically discloses the issue that the IMD signals could interfere with the GNSS receiver in a user equipment supporting LTE/LTE-A technology and Carrier Aggregation functionality, as well as the possibility to avoid this issue by introducing proper signaling.
Paper R4-146495, “2UL inter-band CA protection of GNSS”, Qualcomm Incorporated, Jun. 10, 2014, 3GPP TSG-RAN WG4 Meeting #72bis, generically discloses, in support of GNSS receiver protection, reusing signaling schemes already introduced for interference avoidance for in-device coexistence, or introducing a new or modified signaling.